1. Field of the Invention
The present invention relates generally to devices for pumping liquid, and more particularly to a liquid pumping device that is activated by pressurized gas, and which contains an input chamber, an intermediate chamber and an output chamber.
2. Description of the Prior Art
In nearly every fluid transfer application it is necessary to provide a pump to provide the motive force to move the liquid through a liquid supply line. With the exception of gravitational systems and siphon systems, the utilization of liquid pumps is a necessity and many types of pumps have been developed throughout history. Many of the pumps are powered by rotating or reciprocating motorized devices which tend to create a vibration or pulsation in the pumped liquid and the systems that utilize such pumps. For many applications the vibration and pressure pulsation of such pumps is insignificant and such pumps provide adequate performance.
However, many liquid transfer applications involve liquids having a delicate chemical make-up and chemical processes that are adversely affected by the pulsation and vibration of pumped liquid. For such applications it is necessary to utilize a pump that does not create pulsation and vibration of the pumped fluid. Additionally, many precise chemical processes require strict control of the flow rate of the pumped liquid, and prior art pumps that induce pulsation and vibration within the pumped fluids have difficulty meeting such flow rate constraints. Semiconductor fabrication processes are one such application in which ever stricter constraints on liquid pumping parameters continue to be developed. In many particular applications within the semiconductor fabrication industry pulsation and vibration of pumped chemicals adversely affects the delicate chemical balance of processing liquids as well as the chemical reactions of the processing liquids with the semiconductor substrates in the various fabrication steps.
A need therefore exists for pumps that pump liquids without subjecting the liquids to pulsation and vibration, while providing tight control of the flow rates of the pumped liquids. The present invention, in its various embodiments disclosed herein, provides a pump system that utilizes pressurized gas to provide the motive force to continuously pump liquids through liquid flow lines. The pulsation and vibration created by the prior art pumping systems is eliminated and a strict control of pumped liquid flow rates is obtained.